View Full Version : Fuel pump help
arveetek
11-27-2011, 20:16
I developed a hard start/stumbling issue last week.
Symptoms:
Once in a while it's hard to start, either warm or cold;
Idles just fine, will run fine for a while;
Develops stumbling and hesitation after hard acceleration;
Will smooth out when light on the throttle;
My first thought was a clogged fuel filter, but I only had 8,000 miles on the filter currently installed. However, to rule that out, I changed the filter, but it didn't help. In fact, it seemed to get worse.
Initial tests of the fuel pump showed good: I opened the fuel drain valve with the engine running, and it didn't stall. However, after changing the filter and driving it for a bit, I did the test again, and this time it did stall.
I have Kennedy's OPS harness, so I can tell when the pump is running. I can also easily push a button to manually run the pump, which aids in filter changes. I was able to bleed the system after changing the filter, but it didn't seem to have as much flow as normal out the drain valve.
I decided that it must be time for another lift pump. The first one I installed when I bought the Tahoe lasted 35K miles before it quit. This one had 45K miles on it.
I replaced the lift pump, it started right up, and ran great. I drove it hard several miles, and never stumbled.
Today I drove it again since changing the pump, and after a few miles, the same symptoms appeared. Now when I open the drain valve, the engine stalls again. It's hard to restart. When I do get it started it idles great, but after holding RPMS above 2500 for a while, it starts cutting out and acts like it is starving for fuel.
I don't seem to have normal flow out of the drain valve when running the pump manually. I added 5 gallons of fuel to the tank to make sure gauge is reading correctly (now shows 1/2 tank).
Fuel tank and pickup tube/sending unit were replaced 15K miles ago due to a leak in the tank.
I did verify that the pump is running when the engine is running. In fact, when I unplug the pump harness, the engine stalls out pretty quickly.
So, did I purchase a faulty pump? Or do I need to look elsewhere for a problem?
My plan tomorrow night is to disconnect the outlet side of the pump and try to pump fuel into a bucket to see what kind of flow I have. I'm thinking I have either a restriction on the suction side of the pump, causing it not to be able to pull fuel from the tank, or a restriction on the filter side of the pump, causing it not to be able to push fuel to the injection pump.
Any other insight would be helpful.
Thanks,
Casey
DmaxMaverick
11-27-2011, 21:53
Go through with your LP test. It is possible you got one that's not up to par.
After that, if it checks out, I'd suspect the IP.
bmoeller
11-28-2011, 09:25
I have had the "sock" in the tank plug up and really restrict the flow.
arveetek
11-28-2011, 11:17
I have had the "sock" in the tank plug up and really restrict the flow.
I thought of that, but I just replaced the whole pickup/sending unit assembly 15K miles ago. It's hard to believe that the sock could be clogged after 15K miles when the first one went over 200K miles (I assume it hadn't been replaced before).
You never know, stranger things have happened!
Casey
DmaxMaverick
11-28-2011, 11:27
I have had the "sock" in the tank plug up and really restrict the flow.
The sock is nothing more than a clod sifter (coarse screen). His is new, or it would have been suggested. It takes many years for the sock to be an issue. If the system were so contaminated to plug a "new" sock, other very obvious symptoms would be present, and long before the sock plugs. A first indicator, for example, would be immediate fuel filter plugging, and obvious evidence of the contamination in the filter bowl, and on the filter element. I've seen this happen on a few occasions, and there will be no doubt of the source.
If clean fuel at the minimum pressure (anything above zero) is being supplied to the IP, stalling or poor idling/running conditions can be narrowed to the system between the IP fuel inlet and the injectors, or the return system. Excessive fuel return restriction/resistance can cause this. Something as simple as a failed fuel filler cap vent can cause this. Injectors themselves won't cause stalling on an engine up to operating temp. Bad injectors will generally cause very consistent poor running, across the board. If it starts cold, the injectors aren't the problem. This isn't to say the injectors are not due for replacement, just that they are not the cause of the current condition.
ToddMeister
11-28-2011, 19:11
Maybe run a bit with the fuel tank cap loose. Sounds like the cap is not venting the tank correctly. That would explain the reduced fuel flow and stumbling after a hard run.
This is an easy thing to try first.
Could also have an air leak between the tank and the lift pump inlet.
phantom309
11-29-2011, 21:27
IP is going bad,. my exact symptoms ,. then it quit while idling and wouldn't start till Ip change,.
best of luck,.
Nick
arveetek
12-03-2011, 11:15
Finally had another chance to look at it today.
It's definitely a lift pump issue. IP is fine. I've also ruled out the fuel cap.
I've narrowed down the symptoms to this: I can bleed the fuel filter, start the engine, and drive normally for a few miles, and then it starts cutting out. I can stop the engine, check the bleeder valve on top of the filter, and air comes out. I can then prime the filter again until fuel comes out of the bleeder valve on top of the filter, and then drive normally for another few miles.
So, should I start checking for an air leak between the pump and tank, or look for a restriction past the fuel filter?
Casey
You likely have an air leak between the tank and the lift pump.
Could be a fuel line (metal with corrosion) or a rubber connector hose or possibly the tank pickup safety valve is leaking air.
Missy
arveetek
12-03-2011, 18:38
I'm not sure what I did, but I seemed to have fixed the problem.
I went ahead and dropped the tank to check the rubber hoses and the fuel pickup tube. I took the sock off and cleaned it, seemed fine.... I made sure that the sock sat parallel against the bottom of the tank. Hoses looked good. Put it all back together, took the outlet side of the pump loose and turned the pump on. Seemed to have adequate flow. Hooked the pump back up, and everything seems great!
I noticed right away that now I have pressurized fuel from the bleeder valve on top of the filter. Before I had air coming out first, taking several seconds of the pump running to get fuel to appear. I could also tell the pump sounded different when running.
Drove it around for quite a while and didn't have a single hiccup.
The only thing I noticed was that there was an o-ring sitting on top of the tank when I dropped it down. I'm assuming it fell out of the rubber hose to tank connection when I took the hose off. Surely it couldn't have been sitting there for the last 15K miles, with no o-ring in that connection??
Either that or I didn't have a tight connection at the lift pump....
Cross your fingers and hope I eliminated whatever problem it was...
Casey
I can bleed the fuel filter, start the engine, and drive normally for a few miles, and then it starts cutting out. I can stop the engine, check the bleeder valve on top of the filter, and air comes out. I can then prime the filter again until fuel comes out of the bleeder valve on top of the filter, and then drive normally for another few miles.
How are you bleeding it? are you sure the lift pump is running when the engine runs? Pressure from the lift pump should keep the air out, unless the leak is between the tank and the pump, but then I wouldn't expect bleeding to fix it...
arveetek
12-04-2011, 12:33
Drove close to 75 miles today, no hiccups.
Still not sure what I did....
Casey
Warren96
12-22-2011, 15:27
My "94 had the exact same symptom when the supply line from the tank to the pump got a pinhole leak and let air in. So I have to agree with Robin on this one;The supply line was either leaking or it had a loose connection. Check and see if you have any air in the filter anymore, maybe that is gone also. If it isnt, keep looking, that leak will bite you on the butt again.
arveetek
12-23-2011, 06:47
Well, I have driven the Tahoe for 3 weeks straight without a single hiccup, until last night, when it started cutting out under hard acceleration. Then, this morning on the way to work, it was running pretty crappy again. When I got to work, I checked the fuel filter bleed valve, and the filter was full of air again. Took several seconds of priming the pump manually before fuel appeared. Air is still getting in the system.
So, whatever the problem is, I have not fixed it yet. The same symptoms are present after installing a new pump; but after dropping the tank and putting it back up, it has run great for 3 weeks.
Is it possible that the replacement pump is not pulling/pushing fuel properly? Or since the replacement pump did not fix the problem, that I should look elsewhere?
The fuel line between the tank and hard lines is a special hose w/steel swivel fittings. I assume this will probably be a special order hose...
Hmmmm.....
I know of one way to rule out the pickup and hose assembly including the feed line. Drop the tank, remove the pickup, plug the tank pick-up input and put the whole assembly under vacuum and see if it holds....or charge the assembly and hoses to 5 psi and hit it with bubble spray.
You have a leak before the pump 99% most likely ...unless the pump is failing and admitting air ( very rare).
It probably got better because you moved or retightened something and it worked loose again with time and vibration.
Stay at it.
Does it work when the tank is full and fail when it is (say) 1/4 full?
If the pump is working then it pretty much has to be on the suction side.
Even if the pump was not working, air can't get in unless there is a leak somewhere.
arveetek
12-31-2011, 13:27
Does it work when the tank is full and fail when it is (say) 1/4 full?
I think you have led me to the problem, John.
I hadn't noticed at first, but the problem does seem to only appear when below 1/2 tank. This last time it started failing between 1/4 and 1/2 on the fuel gauge.
Trying to find an air leak on the suction side, I took an old fuel cap and fashioned an air valve into it. I then pressurized the fuel tank to about 10 psi. No leaks found anywhere.
I then decided to drop the fuel tank again. I manually ran the lift pump to pump the tank dry. Hmmmm...upon pulling all the fuel I could out of the tank, the gauge still showed 1/8th full.
I dropped the tank, and found quite a bit of fuel still sloshing around. I measured 4.5" of fuel still sitting in the tank. I measured the pickup tube on the sending unit, and it showed to be around 3" from the bottom of the tank. I bent the pickup tube so that it was closer to the bottom of the tank. I also closely inspected the whole pickup tube assembly for any leaks, and could find none.
I was then able to pump out more fuel, leaving only 2" of fuel in the bottom of the tank. However, at this point, I checked the ohm reading on the sending unit, and it was still not showing empty. I tweaked the float arm slightly so that it now shows empty when the tank is actually near empty.
I put it all back together and filled the tank up. Seems to be running great again. Time will tell.
At this point it appears to be a combination of a mis-adjusted float and a pickup tube too far from the bottom of the tank. Basically, I was running out of fuel. Why it didn't give me problems until now, I'm not sure...unless the sending unit has changed resistance slightly over time causing the gauge to fool me for a while...
Casey
arveetek
01-27-2012, 07:09
I'm still having issues. I've finally narrowed it down to being a problem only when I reach a 1/4 of a tank or less of fuel. It runs great until the fuel gauge shows 1/4. Then it starts sucking air. Last week I hit 1/4 tank returning from a Jeep trip towing my Jeep on a flatbed. Had ran great all day without a hiccup until I got down to 1/4 tank. I stopped for fuel, bled the system, and all was great again.
Last night on the way home from work, I got down to 1/4 tank again, and it started sucking air once again. I had to stop and bleed the system on the way home, and then again on the way to work this morning (have not fueled up yet). Then it died in the parking lot at work. Had to bleed it again to make it the rest of the way in. I've also left the fuel cap loose during this time period to rule that out once again, but it didn't help.
I removed the sending unit and pickup tube several weeks ago, and I could not find a problem, other than the pickup tube seemed to be off the bottom of the tank, which I adjusted. But there has to be a pinhole or something in the pickup tube that causes it start sucking air when the fuel level drops.
I guess I'll see about ordering another sending unit assembly. This one is only 15K miles old. I replaced it because I replaced a leaking fuel tank, and the old sending unit was making the gauge dance around sometimes.
Casey
The Pickup tube has a little valve in it part way up that is spring loaded.
This little device will allow the lift pump to take in fuel if the sock gets clogged.
If this valve leaks air (and many do) as soon as the fuel level gets below the valve it starts sucking air.
Get that pickup assembly out and have a good look at it.
My bet is that valve is faulty.
Was the new pickup assembly a GM unit or aftermarket ??
Keep us posted
Missy
arveetek
01-27-2012, 09:22
The Pickup tube has a little valve in it part way up that is spring loaded.
This little device will allow the lift pump to take in fuel if the sock gets clogged.
If this valve leaks air (and many do) as soon as the fuel level gets below the valve it starts sucking air.
Get that pickup assembly out and have a good look at it.
My bet is that valve is faulty.
Was the new pickup assembly a GM unit or aftermarket ??
Ah! I was not aware of that valve. When I took the sending unit out last time, I did not see anything like that. I still have the old sending unit, I will look at it tonight and see if I can see that valve. That definitely sounds like the culprit for sure.
Is that valve inside the pickup tube itself? I thought mine looked like a simple tube only.
The new assembly was an aftermarket Spectra brand. It was only $80 vs. the $500 + the dealer quoted me! However, I see I can get one from GMpartsdirect.com for less than $300.
Casey
arveetek
01-27-2012, 20:39
Well, it's definitely a fuel pickup issue. I filled up the tank this evening, and she's back to running great again with no air in the system.
When it gets to 1/4 tank, I can barely keep her running. She sucks a lot of air into the fuel system. I can only drive about 6 or 7 miles before she starts sputtering. I can pull over, shut her off, and bleed the air out of the fuel filter, and she'll run good for another 6 or 7 miles. Topped her off with fuel, and all is well again; no more air in the fuel filter.
And the gauge is reading correctly as well. I figured that if I truly had a 1/4 tank of fuel left, it should take around 22.5 gallons to fill her up. I was able to squeeze in 22 gallons. So the gauge is correct.
Somehow, somewhere, the pickup tube is allowing air into the system at 1/4 tank.
Since it takes me nearly two weeks to burn through a tank of fuel, it's been hard to narrow the symptoms down!!
Casey
Burning Oil
02-05-2012, 00:37
FYI: I have a fuel sending unit that we build from scratch. It totaly encloses all the electronics in a stainless steel mast. It won't help with your problem of sucking air, but it is much better than the stock fsu. I call it a Metrum Rod Fuel Sending Unit or MRFSU. Its designed so you reuse your stock pick up and just replase the FSU with ours.
I can email you/anyone the instructions with very good pictures also.
http://www.pmdcable.com/index.php?main_page=product_info&cPath=6&products_id=19
arveetek
02-05-2012, 20:35
The Pickup tube has a little valve in it part way up that is spring loaded.
I inspected the old pickup assembly that I took out of my tank a while back. Just as I remembered, there is no valve in the pickup tube. The tube is just a solid tube from the top to the bottom.
However, after noticing how the sending unit is spot welded to the pickup tube, it makes me think that a possibility exists of the new pickup assembly having a pinhole in the pickup tube where the sending unit is attached. I didn't see anything abnormal when I had it out last time, but that's about the only thing left I can think of.
Right now, as long as I keep the fuel level above 1/4 tank, everything is peachy and rosy! :D
I'll have to see about ordering a new pickup assembly. In a previous experiment, I rendered my old OEM assembly useless.... :( Oh well.
Casey
arveetek
02-12-2012, 14:39
Okay, I'm really starting to scratch my head now....
Yesterday, with 3/4 of a tank of fuel, air got into the system, and I've had to bleed the fuel filter twice now.
I'm really about to pull my hair out! Where is the air coming from?!?!?!
I have a new 'diesel fuel only' green fuel cap, but there is still a slight vacuum when I remove the cap. There's no other vent on the fuel tank, except the fuel cap, correct?
Casey
PS...just to update everyone on the symptoms: Engine runs great until it starts to stumble. Shut engine off. Open air bleed valve on top of fuel filter. Manually run fuel lift pump. Air comes out of top of filter. Takes 10 to 15 seconds of pump running to get steady stream of fuel coming out top of filter (and when fuel does appear, it shoots a healthy, steady stream). Close air bleed valve. Start engine and drive away, and everything is fine, until symptoms reappear sometime down the road.
I thought the air in the system only appeared when fuel level reached 1/4 tank or less. Yesterday it did it with 3/4 of a tank.
Sometimes it will go a couple of weeks without symptoms. Occasionally I will open the air bleed valve on top of the fuel filter with the engine off just to see what happens, and sometimes it will spew fuel out as if under pressure, which it ought to be.
The air leak problem seems to be more and more random. Read previous posts above, and I feel like I have ruled nearly everything out.
Is there anything in the fuel return system that could these symptoms?
Burning Oil
02-12-2012, 15:11
Tank sock getting cloged? then when it does the next week link shows up as an air leak?
Maybe a rubber hose from tank to hard lines or hard lines to FFM. Also orings on FFM. I have nitrile oring replacements if you need a set LMK.
You can blow air from LP suction side of hard line back to the tank with fuel cap removed to knock any crud of the tank sock (atleast temporarily).
Are you sure you're not mistaking a small amount of pressure for a vacuum?
Eliminate the cap as a potential cause by leaving it loose.
As long as the lift pump is working, the only place air can get in as on the suction side of the lift pump.
I agree - there should be NO sign of a vacuum at the filler.
arveetek
02-12-2012, 20:29
"Sock" is new, only 15K miles on the pickup assembly.
I have checked, rechecked, and triple checked hard lines, soft lines, o-rings, etc. from fuel tank to lift pump. I have dropped the tank several times now. I have pressurized the fuel tank to check for any leaks between tank and lift pump. Everything checks fine.
Yes, there is vacuum in the tank. When removing the fuel cap, if I slowly twist the cap off, no sound is heard until I pull up on the cap, pulling it away from the filler. Then I hear and feel the hissing. Letting go of the cap causes it to be sucked back down to the filler. It's not pressurizing the tank, because I would have the opposite signs.
It's not as bad as it was before I replaced the fuel cap, but it is still there.
I'll try leaving the cap loose for a while to see what happens.
Casey
Burning Oil
02-12-2012, 21:34
For diagnostics maybe try a temp fuel system. Use a marine 5 gallon fuel tank & pump plumbed straight to the FFM and bypass everything else?
arveetek
02-13-2012, 13:00
After pondering it a bit more....
Maybe I should re-phrase what I've been stating.
The reason I say that air is getting into the system is because the engine bucks and will almost stall, and then I have to manually run the pump to fill the fuel filter housing back up.
Looking at it from another view point: when the symptoms appear, the fuel filter housing is nearly empty. I open the bleed valve on top, run the pump until fuel appears, and then close bleed valve.
What's happening is that the fuel filter housing is not filling up with fuel. The engine is basically running out of fuel. I have checked every single component for air leaks. What if the system is not sucking air....what if the lift pump cannot overcome some other issue and is not able to pull fuel from the tank? Whenever I stop, open the bleed valve, run the pump, etc... it is overcoming whatever obstruction there is, pulling fuel from the tank, and filling the filter.
I have been assuming that the lift pump has been sucking air, since fuel is not present in the filter housing. If I DON'T open the bleed valve before manually running the pump, then of course it does try to compress the air already in the filter. If I open the bleed valve after running the pump, then air does come out. But if I open the bleed valve first, and then run the pump, it simply runs for a while before fuel appears.
So maybe I'm going about this all wrong. Maybe the problem is not an air leak. What could be preventing the lift pump from pulling fuel and pressurizing the filter housing?
It's as if the engine is using more fuel than the lift pump can supply. Eventually the housing empties of fuel, and I have to stop and manually refill the housing.
When the problem first surfaced, I assumed a failing lift pump. Replacing the lift pump did not make the problem go away.
I left the fuel cap really loose on the way to work this morning. By the time I got to work (22 miles), it was starving for fuel again.
I sure do appreciate all the help given so far!!!
Casey
PS....at the very beginning I verified I had a running lift pump when the engine was running...I better double check that again.
Burning Oil
02-13-2012, 13:24
Dirty fuel sock!
What pressure do you have on LP? IMO a fuel pressure gauge is the most important gauge for diagnosing problems. You can red neck it and put a gauge on the drain from FFM & run it to the windshield so you can monitor PSI while driving. A LP might give normal #s in the driveway, but on the road is where you need to know. Coincidently I sell a LP & pre filter and LP bypass fittings if it turns out you need a LP LMK. Check your sock first or remove it and install my kit.
Leroy
arveetek
02-13-2012, 14:25
Like I have mentioned a couple of times, the sock is nearly brand new. I have pulled it out twice, and she's clean as a whistle.
Burning Oil
02-13-2012, 14:36
Only takes one fill up of bad fuel. Its got to be LP, dirty sock or air.
One more thing and you would know this with a gauge is the OPS could be faulty, but then again I believe your runs off the PCM after start up?
What year is your truck?
I installed the Walbro FRC-10 Fuel Lift Pump and bypass fittings from PMD. I also installed a Ricor pre-filter.
I posted some pictures under "coxfmly" showing the set-up with a bracket assembly I fabricated.
arveetek
02-13-2012, 20:59
I did some more diagnostics tonight. I really wish I had a fuel pressure gauge.
Here's some more info:
With the engine off, running the lift pump manually produces a steady, healthy stream of fuel out of the top of the filter with the bleeder valve removed. It nearly shoots out the top of the filter about an inch.
With the engine idling, the fuel dribbles out of the top of the filter with the bleeder valve removed.
With the engine at high idle (1200 rpm), there is barely any fuel visible coming out of the top of the filter with the bleeder valve removed. Sometimes there is no fuel at all coming out, sometimes it dribbles out. I would call this 0 psi at high idle.
I verified that the lift pump is running when the engine is running. I installed a small light on the fuel pump circuit. So it's not an OPS or harness issue.
I'm really starting to lean towards a weak lift pump. It seems to be able to provide pressure when engine is off, but little to no pressure when engine is running. It doesn't seem to provide enough fuel at higher rpm.
Is there anything else in the fuel pathway or Injection Pump that would cause the fuel lift pump not to be able to keep up with demand?
I've been chasing this problem since before Thanksgiving. Perhaps I just replaced a failing lift pump with a new faulty pump. :(
Casey
On edit: The new pump is an Airtex brand. The previous pump was the same Airtex and it lasted 45K miles. The pump before that was an AC Delco and it only lasted 35K miles.
Burning Oil
02-13-2012, 21:29
Sure is sounding like a weak pump. Get a cheap 0-15 psi gauge and hook it to the FFM drain with a hose long enough to reach windshield so you can see it while driving. OR, I do sell a Fuel Pressure Tap that screws onto the filter. It provides a very easy way to see LP pressure.
http://www.pmdcable.com/index.php?main_page=product_info&cPath=6&products_id=2
http://www.pmdcable.com/index.php?main_page=product_info&cPath=6&products_id=17
http://www.pmdcable.com/index.php?main_page=product_info&cPath=6&products_id=9
How are you powering the lift pump with the engine off? The engine does not use that much more fuel at idle than when off, so something else is causing the difference in flow.
You could try powering the pump however you do when the engine is off, when the engine is running to see if it makes a difference.
DmaxMaverick
02-14-2012, 21:15
How are you powering the lift pump with the engine off? The engine does not use that much more fuel at idle than when off, so something else is causing the difference in flow.
You could try powering the pump however you do when the engine is off, when the engine is running to see if it makes a difference.
It's a 95. The pump will run anytime the key is in the "start" position. If the gear range is anything but P or N and you turn the key, the pump will (should) run with no cranking.
master53yoda
02-15-2012, 05:19
The other possibility is a oil pressure/fuel pump switch that is going bad but hasn't completely failed yet. If the resistance is high on the oil switch it will slow down the pump reducing its pumping efficiency.
Can you use your primer button to bypass the pressure switch with the engine running. If so when you have low flow, energize the pump with your prime switch,if you get increased flow then that would verify a bad pressure switch.
If it is the switch it will progressively get worse, until it won't work at all. When i put transfer pumps on i energize the pump through a relay that is operated by the switch rather then using the switch to drive the pump.
good luck
arveetek
02-15-2012, 06:51
Thanks guys! I appreciate the responses. I am running Kennedy's OPS relay harness, so the pump is energized by his relay kit, and not directly off the OPS. I have verified that the pump is receiving good, steady power with the engine running. I have a button on the firewall that allows me to energize the pump whenever I wish. I have also tried running the pump manually with the engine running with no change.
Casey
OK, so we can probably assume the pump is working to the best of its ability.
That leaves 2 questions:
1) how is the air getting into the filter?
2) why is the volume of excess fuel so low when the engine is running?
The first one is easy. It has to be getting in on the suction side of the pump.
The second one is more puzzling. Could the injection pump be bypassing too much fuel?
DmaxMaverick
02-15-2012, 14:39
If the IP were bypassing (returning) too much fuel, it would do it at idle too, and temperature would be a much bigger player. Sounds like a weak lift pump, coupled with an otherwise insignificant air leak (only leaks under suction, which is quite common). Or.... You have a big leak between the lift pump and tank.
If the IP were bypassing (returning) too much fuel, it would do it at idle too, ...
I agree, but I think he said he had good flow out of the filter breather with the engine off, but just a trickle at idle and nothing at higher RPM.
arveetek
02-15-2012, 20:43
I have checked, rechecked, and triple checked for leaks between the lift pump and tank, and cannot find a thing. I'm really suspecting a weak lift pump.
I picked up another lift pump today, and am going to swap it out tomorrow night. Hopefully that will take care of it.
Fortunately my current pump is still under warranty, and the parts store has no problem swapping pumps with me.
Wish me luck!
Casey
I didn't read all of the posts,but if it has not been mentioned the dip tube on the sending unit has been known to get pinholes from rust inside the fuel tank that allow air entry when the fuel level falls below the hole.
Also the lines leaving the sending unit are prone to rust from moisture and debris settling on them.
The rubber O-ring where the fuel line from the tank enters the LP if damaged or dried out can also be a source of air entry.
arveetek
02-16-2012, 20:38
Swapped out the pump tonight. I immediately noticed more flow, and now when the engine is idling or even at high idle, fuel squirts out pretty strongly when I open the bleeder valve on top of the fuel filter.
Cross your fingers and hope that this was the problem all along!!
Casey
More Power
02-17-2012, 10:42
Was the first replacement lift pump an imported unit? I've heard from 6.5 owners these past 2-3 years about imported (China) pumps not performing very well or failing soon after installation.
Burning Oil
02-17-2012, 10:48
Swapped out the pump tonight. I immediately noticed more flow, and now when the engine is idling or even at high idle, fuel squirts out pretty strongly when I open the bleeder valve on top of the fuel filter.
Cross your fingers and hope that this was the problem all along!!
Casey
Should be good to go! (for 9 months)
arveetek
02-17-2012, 12:30
Drove to work just fine, went to lunch, came back from lunch and she ran out of fuel in the parking lot.
This pump is an Airtex brand, probably a China model. I haven't looked closely at the box.
Recap of the symptoms:
Engine started sputtering under load. Checked pump (Airtex brand with 45K on it). Did not appear to be pumping well, replaced pump. Did not solve issues. Still running out of fuel (filter is empty). Can manually prime filter and runs great for a while until it starts sputtering and bucking - check the filter and it is empty. Replaced pump with another unit, still running out of fuel.
I have verified pump is running and has constant power when engine is running. I have dropped the tank twice to check for leaks, and the sending unit/pickup assembly only has around 18K miles on it. "Sock" on pickup is clean as can be. Symptoms appear no matter what level the fuel is. New diesel fuel cap on tank.
I'm getting really stumped on this one...unless I am just getting crappy pumps that are no good.
Casey
Have you checked the screen in the filter manager that sits on the mast/fuel heater under the filter?
If it is plugged it might be enough restriction to let the IP empty the housing?
DmaxMaverick
02-17-2012, 13:36
While "outgassing" can occur with fuel under vacuum, you are seeing too much, too quick for that to be the issue. You have a leak you haven't found, likely between the lift pump and tank. Check all the connections, and the line, again. You may have a leak that only leaks under vacuum, but doesn't under pressure. I know it sounds like a broken record, but it keeps coming back to this.
Burning Oil
02-17-2012, 14:25
My gut keeps telling me the sock. Only other thing I can think of is a problem I have had. It Would make the truck not able to exceed 30mph, but it would not buck. The problem was the hard line going from LP to FFM was pluged. I ran a hose into a clean bucket and blew compressed air from FFM side (where the rubber hose connects) down to the bucket. All kind of crap came out of there. Truck has run great since.
You can also blow back to tank at the LP connection (remove cap first)
You really need to hook up a fuel gauge!!
arveetek
02-17-2012, 18:14
I'm going to have to take a harder look at the line between the filter and the lift pump. It was running so bad tonight, I didn't think I was going to make it home! I have a 22 mile drive home from work, and I had to stop 3 times to bleed the filter. Each time it got worse and worse, to the point that fuel would not pump up to the filter. The last time I couldn't get more than 3 miles. Then it wouldn't pump fuel hardly at all. I ended up taking the filter out, and it took maybe 2 minutes to get the filter housing full. Fuel was barely trickling into the housing. What's funny is that there were no air bubbles in the housing when the pump was running.
The pump sounded like it was working hard too. Almost sounds like a restriction between the pump and filter....
Burning Oil
02-17-2012, 18:53
Could be a restriction on the suction side to. Blow the lines out.
a5150nut
02-17-2012, 19:36
Have you got any algie growth in the tank?
You need to unhook the line at the filter and then at the pump, blow that sucker out with air and make sure its OK.
The line sets used on these trucks have a metal component as well as a rubber section.
What may have happened is that the rubber portion of the line has degraded inside the CORE and has basically swollen shut.
I have seen this before and the symptoms sure fit the problem.
Have you used Bio diesel in this rig. Some Bio stuff can cause issues with hoses.
The fuel lines sort of snake up and over the back of the tranny and then connect to the filter and the return line.
What I did on one rig was to cut the feed line to the filter right near the lift pump and then installed a ferrul on the line. ( just used a ferrul fitting, tightened it then removed the fitting and cut the nut off.
You could take the line out and sweat solder a ferrul on.
The ferrul will allow a safe install of a Heavy duty rubber fuel line without it being able to slip off when clamped.
Run a new rubber line up under the drivers side floor board (clamp as needed) snake it around the Hydro boost and then across the LH VC and connect it to the filter.
I do not recommend running the rubber line across the tranny.
Too much chance of it getting worn through due to vibes and engine movement.
Now, If you want to fiddle around, you may be able to remove the old rubber line from the fuel line harnes and then do the ferrul thing and install new rubber and leave the lines where they are.
I swapped locations on mine while the engine was out due to the line bracket being such a PITA to get the nuts on an off of the studs at the top of the bell housing.
Check this area out and keep us posted.
Missy
arveetek
02-18-2012, 19:44
Yes, I have run quite a bit of home-brewed Bio Diesel through this rig over the past 5 years. It's been a few months since I've run any, due to cold weather, a busted pump on the processor, and low oil supply.
It crossed my mind that perhaps the fuel supply hoses may be be swelling internally and restricting flow, just like the brake line hoses do from time to time....
Casey
I would certainly have a peek see at the hoses. The metal lines are imune to most stuff other than water and corrosion rust through.
All it would take would be a little flap of rubber thats flipping into the stream and closing off the flow.
Unhook the feed line from the lift pump and then fire off the pump and see what shakes.
Betcha the fuel flows good right at the pump :)
Good luck
Missy
Yukon6.2
02-19-2012, 20:24
Hi Casey
Had a similar problem on my skidder,would run great for about 1/2 hour then begine to lose power till it would bearly idle.Change filter all was good for the same time,over and over.Turned out to be a bunch of stuff in a brass elbow.It would slowley plug the elbow as it was running.Shut it off and it would begin to slowly sink down stream.
I found the problem by using a jerrycan as a fuel tank,hooked it up and the skidder ran great for hours,had better power too.Previous owner had just changed the injection pump chasing fuel problems till he busted the tranny.He mentioned the new pump,but failed to mention the ongoing stalling.
Good Luck
Thomas
arveetek
02-21-2012, 19:33
Last night I took everything loose from the lift pump forward. I completely removed the filter housing and found a layer of what I would call 'tar' down in the bottom. It was some nasty stuff. I guess 240K miles and years of differing kinds of fuels had taken its toll on it. I completely disassembled the housing and thoroughly cleaned it and put it back on.
I also blew air backwards from the hose connected to the inlet of the fuel filter back to the disconnected hard line going to the lift pump. Surprisingly little debris came out. It seemed to have really good air flow, so I buttoned everything back together to see if anything changed. I appeared to have better flow to and from the filter, so I drove it to work this morning, or should I say, attempted to drive to work.
I made it about 6 miles down the road before she started sputtering again. Pulled over, popped the hood, and checked the filter...no fuel at bleeder valve. Had to run the pump quite a bit before a trickle of fuel finally came out the top of the filter. Decided to turn around and head back home. Long story short, tried bleeding the filter several times, and got within 3 miles of home, and ended up calling for a tow back to my house. I couldn't even keep enough fuel up to the engine to keep it running.
Haven't checked anything else yet, but the problem is getting worse and worse which means I HAVE to be able to pinpoint the issue!!
Next up on the list is checking the suction of the pump (again) for restrictions. If that doesn't turn up anything, I'm going to try running a few miles on an aux tank and bypass the main tank.
It seems to be that when sitting still and after sitting overnight, the pump works great. After driving a few miles, it's like something is shaking loose and restricting the flow of fuel. It's rather frustrating to keep running out of fuel when there is plenty in the tank!!
I'm hoping to get it running again and drive it a bit until it quits, and then immediately see if I can tell where the restriction is...suction or pressure side of the pump. So far, by the time I'm able to work on it, everything is back to normal. Now I need to try to catch it in the act, so to speak.
Casey
Air leak between the fuel in the tank and the LP,or a clogged fuel sock on the sending unit,or a plugged vent in the fuel cap are the most likely cause of your problems.
Without re-reading your whole post could you let us know how you power the LP when bleeding?
Have you opened the WIF Tee-valve when the engine idles to ensure the LP is pumping while the engine runs?
stezloco
02-24-2012, 03:56
you could try to connect a container of fuel to your lift pump to take the tank out of the equation....it sounds like since youve lost your fuel at the filter that youre either pulling air before the lift pump or have a blockage in the tank /cap/fuel filter or lines (which will also pull air thro' joints you thought were tight) hence no fuel at the filter.the F.i.P'S trying to deliver it but theres little or none coming to the pump.go back to basics before you hit your wallet ....achems razor(?) it is often the simplest thing at fault.start with the cheapest things to diagnose...I'm thinking old skool here tho' and with a miriad of electronics 'making your day' it makes the diagnostic process harder. start with the basics first tho' and then go on to prove your lift pump on the move with a fuel pressure guage tee'd in.after proving tank/pump filter youre firmly in electronic pumpandwiringland ... and there are a wealth of brains here to help you out.
i once had a garbage truck with a similar intermittent run/stop problem...pointed to the fuel system but where to start..i eventually worked my way BACK to the fuel tank (so i would START there first) and found a pvc workmans glove in the fuel tank....they had just fired one of the ops that morning coincidently. he got his own back.aint life great... :¬)
arveetek
02-29-2012, 20:38
After reading this article:
http://www.thedieselpage.com/members/features/model80c.htm
I have come to the realization that there is no screen at all in my filter housing. I don't think I've ever seen one in there. So I need to remedy that. I have read that several people go with a Racor filter setup. Any recommendations?
I also found this article:
http://www.thedieselpage.com/members/features/returnflowc.htm
This sounds very similar to what I am experiencing. I noticed, in my opinion, what was a large amount of fuel being pumped out of the return system of my IP. I'm starting to think that excessive fuel return could be part of this ongoing issue.
My SES light has been disabled. What is the next best way to read codes (1995 model)? Or would it be simpler to fix the SES light? I believe I am having serious injection pump problems now. She won't run without blowing tons of smoke and shaking terribly....like the timing is way off. I'm pretty sure the IP is toast, but I want to pull some codes and do a good job of diagnostics before I start replacing parts.
Thanks,
Casey
Hello RVTEC;
I have the exact same problem, I mean exact same and have done exaxctly what you have done, and I have finally given up after almost two years and brought it to a garage. They have had it for three days and now say it is the lift pump. I told them that I have changed it multiple times, but what the heck, let them try it.
One thing that I have found is that these lift pumps do not like to self prime, ie a little air in them and they just do not pump.
About a year ago, I fixed the problem for about three months by cleaning off dual battery terminals because lift pump was getting low voltage. Makes me think that these pumps are very sensitive to voltage, and while driving, start and stop pumping, get an "air lock" and then stop pumping. Only thing that I can think of.
This is so weird, I could have written your exact postings.
1997, 2500 Subway, 200 K miles.
Regards,
Wayne
Hello Again:
The more that I think about it the more sense it makes. Voltage to pump drops lower for a bit and pump stops pumping but may still make noise. Somehow gets some air in it, maybe from on/off pumping and then will not prime. May overheat, thus sometimes requiring the truck to rest a little before it will work again.
I don't know, just guessing, as this has been driving me crazy for years.........
I did try jumping the relay so pump would run allways, but no change, thus this may not be the problem. I have tried everything.
Regards,
Wayne
arveetek
03-02-2012, 07:13
I hope you get yours figured out, Wayne. Let us know what happens.
In the meantime, my rig is down for the count. She won't even drive now. I'm waiting for some more time to run some diagnostics, but everything is pointing to a failing injection pump. She'll start and run, but she'll blow tons of smoke and shake the whole truck badly. The timing is all over the place. I'm thinking the optical encoder sensor may have died again. And this may be a result of poor fuel delivery over the past few months.
I went ahead and ordered a Racor fuel filter setup yesterday. I'll get that installed and then move from there. I am definitely not pleased with the factory fuel manager system. If I end replacing the IP, I want to make sure the new one has a steady source of clean fuel.
Casey
Hello RV:
Please let me know how it works out with yours. I hear that letting the IP pull all the fuel instead of the LP is bad for it??
I have not heard anything from the garage today so I bet the new LP is not any better, like I told them.
I do know that when the LP was working, the overall performance of the truck was much improved.he
I went through two IPs under warranty, and after the third failed I replaced the driver with one on a heat sink and so far so good after 50 or so k.
Keep me posted and good luck.
Regards,
Wayne
The lift pump should have no problem priming itself.
It also should not get air in itself unless the fuel level in the tank falls low enough to allow air into the pickup. If it does, then there's a leak somewhere between the pickup and the pump.
If it's clicking it has enough voltage to pump. It only clicks when the spring inside has forced the fuel down the line. The click is the "intake" stroke of the pump. The spring provides the pressure. If it clicks and doesn't pump then it may have air in it or the check valves may have failed.
stezloco
03-03-2012, 01:53
Its an expensive misdiagnosis to replace an injection pump only to find your fault is still with you.....
I would try all of these first:-
remove/clean the fuel tank/sock (mine stood for a year and was full of brown crud/bio-organism that grows in water /diesel)
blow out all the fuel lines from ip back...
ensure fuel cap breathes..
test pump itself using 12v supply and 'suction' pipe dipped in fuel container....make sure it flows fuel from one container to another..not worried about pressure just yet..
fit new filter and prime system using a vacuum pump at the water in fuel drain point(after your little tap on the thermo hsg)
crack off 3 or 4 injector nuts that you can reach easily
get someone else to crank/start engine while you look at injectors that have been cracked...
shut it down/stop cranking when you can see fip 'spurting'a little fuel from the cracked open ends..
fit a fuel pressure guage to that drain line (extend it if you want so you can see it from driving position)
retighten and start engine....if engine wont run try partially clamping the fuel return line at the ip but leave it with some flow....ive read about people suffering what they think is excesive fuel return flow but cant understand why (or is there , experts help me out here) there isnt a fuel restrictor in the return line to keep the fuel pressure up at the ip within tolerance range (i know overpressuring it affects timing)
I'd rather chuck some money at a few cheap diagnostic tools ie guage/fuel line/spare pmd than a lump of cash at the wrong thing...if youre satisfied youve done all you can i'd ask a diesel specialist who knows these engines to diagnose it as well....
if youve got a spare pmd (should be remote mounted behind bumper) fit it in place of yours...
repair your ses light (best indicator of fault) follow procedure in 'the diesel page' for jumping terminals to read off the flashes.
if it wont run at all check your harmonic balancer is serviceable and get someone to hold the ring gear (remove starter)with a screwdriver while you turn the crank from the front to check if its broken.
mech injection pumps usually wear out slowly over a period or some linkage gives out inside the pump but these solenoid controlled ones present extra diagnostic problems... i dont envy you...good luck tho'
Hello All;
End of saga I hope. The diesel mechanic tried everything, including new lift pump. No change.
Finally after pulling the tank they noticed that the pickup sock was clogged up a bit, then they noticed that there was no check valve pickup to bypass the filter when it was clogged. Then they realized that the sender unit in the tank was for a gasser and not a diesel, so the sock was much finer and no check valve when clogged.
They removed the sock and now no problem.
All out there with this problem, check to see if the sock is clogged and if it is the correct sender unit, gas ones are different!!!!!
Now, is it ok to run without the sock???? as they did not want to replace the whole unit??
I seriously dislike auto parts places that are not carefull in what they supply.
Regards,
Wayne
arveetek
03-05-2012, 11:54
I have read about the check valve bypass, but neither the new pickup assembly I purchased nor the original OEM unit had one.
I would think that a gasoline assembly would not have the correct fittings. Also, the gasoline rigs of the same vintage trucks had the fuel pumps inside the tank. So, I doubt your pickup assembly was actually made for a gas rig.
I believe that some of the pickup assemblies had the bypass, some didn't.
Casey
It seems as though some aftermarket suppliers use the same fuel sock for both gas and diesel sending units to cut costs/inventory-the result is a poor performing product.
This is too strange. The diesel mechanic said the strainer was definitely from a gasser as he compared it with one from a diesel and said it was much coarser.
What do you all think about running without a strainer to eliminate this nonsense, and just change filters more often???
I would have thpought that the gas unit wouold have been much different also, so must be the wrong strainer issue???
Regards,
Wayne
I would remove the strainer completely and then add an inline filter before the LP.
Dorman makes short fittings with the proper fitting for the LP and sending unit with a hose barb to allow diesel rated neoprene line to be run between them,get that at most parts stores and then add the inline filter where it fits good for changing.
fitting for example only:
http://www.dormanproducts.com/carquest/p-4002-800-240.aspx
phantom309
03-05-2012, 18:39
This thread http://www.thedieselpageforums.com/tdpforum/showthread.php?t=39905
might give you an idea for an alternative fuel filter,.and an alternative fuel
pump,.
http://i39.photobucket.com/albums/e157/wtfuashols123/MVC-014S-3.jpg?t=1324163476
http://i39.photobucket.com/albums/e157/wtfuashols123/MVC-075S-1.jpg?t=1323563124
Nick
Hooptybass
03-05-2012, 18:54
Ill try and get some pics on the set up i run on my 94 burb tomorrow for an idea
Mechanic said that the filter sock had some waxy tan stuff clogging it. Tank and filter were otherwise clean. Truck is running beter than it has for several years.
Will keep an eye on the main filter.
So far so good. This has been a major pain over the last several years and finally seems to have been solved.
Regards,
Wayne
DmaxMaverick
03-06-2012, 09:40
The sock is not the problem. Ever. If it's plugging up, you have fuel quality problems, regardless of the screen size. I've seen them in various sizes, OEM and aftermarket, model to model and year to year. They are all sufficient to do what they need to do. It's there for a reason, and it sounds like it did its job (Wayne). Your tank and fuel may be "otherwise" clean, but it apparently wasn't always. Removing it defeats the fuel system's first line of defense. A pre-pump filter is not a bad idea, but it doesn't replace the sock. A "mechanic" who removes the sock (to "fix" the problem), because it's fouled, is no mechanic.
stezloco
03-06-2012, 10:29
I kindof agree with both of you regarding the sock thing...its needed but just not there in the tank...its hard to get at it in my pickup so I'm doing away with the sock in the tank when i get to it and fitting an agglomerator (or crap trap) with a big plastic see thro'bowl and drain so i can see the crud thats collecting (racer55 )....theres a fine mesh filter in the top of the agglomerator, i figure if its small enough to get past the mesh filter, then the pump can send it on to the main filter (phantom 309..NOW THATS A FILTER ! !)
Anyway it sends the problem further up the line but at least i would only have to get on my back to see the trap bowl and act accordingly from there. the sock over complicates the system it can be moved 'down the line 'so to speak where its easier to deal with.
isnt it a massive relief tho' you didnt go for changing the F.I.P??
I agree with D Max. Talking to various locals about this problem brought up the issue of where I typically get my fuel, and then all the rumors come out about the fact that this station is known for water in diesel etc. Makes me wonder.
I was not overjoyed when the mechanic told me that the sock is gone, but is was all back together and the thought of pulling the tank was not what I was looking forward to doing this weekend.
I will try and find an in line filter, seperator, before the lift pump to replicate as much as possible the in tank filter.
Also will try another local station for diesel fuel, but I bet they get it from the same distributor.....
At least it is running better and smoother than it has in years.
Regards,
Wayne
DmaxMaverick
03-06-2012, 10:45
That's pretty complicated. A lot more complicated and costly than the original design. In the end, may be less effective. The sock does more than just "filter" crud. It enlarges the uptake square area. If you have only a pipe, it won't take much debris to stop it up. Fuel tank obstruction happens, especially during winter. If your fuel begins to cloud, a little wax will plug the line. The sock prevents this temporary condition, most of the time. A marble or pebble will do the same thing. Fuel tank sender units are accessible by several means. If you need to access it, then something went wrong, and you should be in there. If your "other" filter system shows you some contamination, then you have to get to it, anyway. If a condition presents itself that would plug the sock, your high-dollar system will plug that much sooner. You don't control your fuel quality. You accommodate it. When you get a bad tank, a finer filter will stop the flow much sooner. When this happens, a course strainer in the tank is the best defense. The fuel manager will protect the downstream fuel system. They are also more restrictive, which may shorten lift pump life.
Be very careful when you try to out-think the engineers. The OEM design (of all vehicle brands, which are very similar), for the most part, has been extremely reliable and effective for nearly a century.
I'll repeat. If your sock has problems, the sock isn't the problem. Address the cause.
Yeah, to rephrase, it takes hundreds of moderate size particles to clog up the sock, but only one to clog the pickup tube...
Hooptybass
03-09-2012, 17:20
Here is a few pics of the setup i have on my 94 K2500 burb
http://i288.photobucket.com/albums/ll165/hooptybass/DSC_0014.jpg
http://i288.photobucket.com/albums/ll165/hooptybass/DSC_0017.jpg
http://i288.photobucket.com/albums/ll165/hooptybass/DSC_0016.jpg
http://i288.photobucket.com/albums/ll165/hooptybass/DSC_0018.jpg
Hope i did this right .....hehe
arveetek
03-14-2012, 07:23
I got the IP replaced on the Tahoe, and now she is running again. However, I'm still having fuel supply issues.
I now have a Racor filter setup with a fuel pressure gauge installed. I was able to watch as the fuel pressure slowly dropped to zero after running for about 30 minutes. I took the suction side of the pump loose and put a hose on it and dropped it into a bucket of fuel. It wouldn't pull any fuel. I then put my finger on the end of the suction hose, and I didn't feel any suction at all. Next, I disconnected the outlet side of the pump, just to make sure there was no restriction. I ran the pump again, and absolutely no suction at all!!
Apparently, these Airtex pumps I've been getting are pure junk!! :(
Any recommendations on replacement lift pumps? I know AC Delco, Kennedy's Duramax pump, and the Walbro pumps are all options. Any other suggestions?
I might as well put the best in after doing all this work!!
Casey
Burning Oil
03-14-2012, 07:33
Did you prime the pump while doing your testing?
Here is another LP option. A Raptor 100.
http://www.pmdcable.com/index.php?main_page=product_info&cPath=6&products_id=43
DmaxMaverick
03-14-2012, 08:38
Put this monster behind you. How much $$ have you "saved" by going outside the tried and true? AC Delco, or the Kennedy Pump(s). Just do it and be done with it. Or, keep this thread going for really long time.
If the pump is good and operating normally, it should NEVER need "priming". The pump should self-prime, every time. If it requires priming, either you have the wrong pump, or it's bad.
When evaluating pump options I suggest you do a web search on the name, add the word pump and then variable keywords like quit, leak, issue, fail, loud, noise, rough and I think you'll be surprised what you find (or don't) for some suggested here.
arveetek
03-14-2012, 09:57
Put this monster behind you. How much $$ have you "saved" by going outside the tried and true? AC Delco, or the Kennedy Pump(s). Just do it and be done with it. Or, keep this thread going for really long time.
I wasn't necessarily trying to save anything. I did the "tried and true" thing when I first bought the Tahoe. I installed an AC Delco pump that I bought from Kennedy. It lasted 35K miles. I then bought an Air Tex unit since I was in a hurry. It lasted 45K miles. I saw no need to go back to the "tried and true" since it didn't last as long as the second replacement unit.
Apparently I was just lucky with the first Air Tex pump. I have learned the hard way that I need to purchase a better pump. My experience has told me that an AC Delco pump actually had a shorter life span than an Air Tex. Therefore, I thought I would ask for other options.
I'd rather find a pump that I can install and just forget about it for a long, long time. Maybe that's wishful thinking.
Casey
DmaxMaverick
03-14-2012, 10:24
I understand, but that's one failure and one success, on one vehicle, contrary to the standard. Seems you got a bad Delco, and a good AT. This can happen with any component at any time, to anyone. The Delco pumps, on average, perform vastly better and longer than any other OEM type pump. They usually cost more, for sure, but the "value" is normally in their longevity. Even if you get a "lifetime warranty" component, for less money, how do you value your time, if you have to replace it a few times? If you are getting abnormally short lived pumps, maybe it isn't the pumps. I'd start looking at fuel quality or electrical problems.
With your current problem (this thread), you MUST solve the fuel delivery problem before considering anything else fuel related. Without consistent fuel delivery, everything else downstream won't be right. So far, it's likely the cause of your pump failure, although the pump was likely weak. The lift pump problem probably just pushed it over the edge sooner than it might have, with a good supply of fuel.
All this talk lately about fuel tank socks is hogwash. Pure and simple. There is no difference between a Diesel or gasser sock. Some are more fine than others depending on supplier source, but the fact remains, if this very course screen (even the finest "gasser" version) is plugging up, the problem isn't the sock. Removing it, in favor for a MUCH more restrictive filter, is ludicrous. If you had a problem with plugging socks, then replace it with a filter that's 100's of times more fine, the problem will just be relocated, and probably exaggerated. Forget the sock. If it's plugging up, fix the problem.
arveetek
03-14-2012, 11:27
Even if you get a "lifetime warranty" component, for less money, how do you value your time, if you have to replace it a few times?
I agree 100%. I've tried to stop buying "lifetime warranty" parts whenever possible. I've learned that "lifetime warranty" actually means you'll spend your lifetime changing those parts!
With your current problem (this thread), you MUST solve the fuel delivery problem before considering anything else fuel related. Without consistent fuel delivery, everything else downstream won't be right. So far, it's likely the cause of your pump failure, although the pump was likely weak. The lift pump problem probably just pushed it over the edge sooner than it might have, with a good supply of fuel.
Yes, I believe my original DS4 was getting ready to die, and the fuel supply issue finally caused it to crash.
All this talk lately about fuel tank socks is hogwash. Pure and simple. There is no difference between a Diesel or gasser sock. Some are more fine than others depending on supplier source, but the fact remains, if this very course screen (even the finest "gasser" version) is plugging up, the problem isn't the sock. Removing it, in favor for a MUCH more restrictive filter, is ludicrous. If you had a problem with plugging socks, then replace it with a filter that's 100's of times more fine, the problem will just be relocated, and probably exaggerated. Forget the sock. If it's plugging up, fix the problem.
I agree 100% with this too. My sock is still installed and doing its job (I'm not the one with the removed sock).
It appears I've simply gotten two defective pumps (made in Mexico, for whatever it's worth).
Casey
Burning Oil
03-14-2012, 15:11
The removal of the tank sock and istallation of a 30 micron filter is what I recomend highly. The tank sock is what 70 micron?
The idea is to make life easier. If your having problems its much easier to replace a spin on filter than to clean a tank sock.
If you are having issues with having a dirty sock then yes that needs to be corrected, but I would much rather deal with a external filter than drop the tank because sometimes the reason for a dirty sock can be ongoing and you may have to drop the tank several times before its cured.
Also, the Walbro FRC10 like I sell is the perfect choice at $139 for the ds4 IP trucks. In all I have sold I have not had a single failure yet.
The ds4 IP needs 9psi and the walbro is delivering a constant 10psi unless at WOT it may drop to 5??
stezloco
03-15-2012, 03:12
@BURNINGOIL
my thoughts to your thoughts Mr Spock....
thats a great looking pump ,just the price puts me off. is the fuel pressure that critical that it needs EXACTLY 9 psi? isnt a positive pressure feed still positive?
@dmax
I agree,It is time this thread bit the dust so to speak, and you know what , youre ALL CORRECT...there dont seem to be any wrong ways to filter/deliver fuel...just many ways to 'skin this cat', and there are many ways as we all have said ,some better than others though.
CLEAN TANK+CLEAN FUEL= NO PROBLEMS AMIGO..
I cant agree more about tank removal, it is a ball-ache and PERSONALLY, this is just me, i prefer the out of tank pre-filter or agglomerator idea so i dont have to empty and lug that big tank everytime i suspect a blockage.
all the years i worked on wagons i rarely had problems with fuel pickup pipes (just the things that were put into the tanks deliberately) and none of them had tank socks...draw your own conclusions from all this very good advice ive read here on this subject.....oh ....and dont forget to treat your fuel with BIO-KILL if you are going to stand it for a while, the brown sludge monster will come visit if you dont....ive met him ...
cheery bye...
arveetek
03-15-2012, 05:55
Sheesh!
Looks like I stirred up a hornet's nest here!
I decided to stick with a stock pump, and ordered a new AC Delco from Kennedy. John has always been good to me and answered all the questions I've had.
BTW.....Kennedy's price on the Delco pump is as good as most anywhere...including Rock Auto.
Casey
john8662
03-15-2012, 07:09
Casey,
I know you've got your OPS bypassed so to speak with the Kennedy setup, but it's powered somewhere different than it would be from factory.
Maybe you've got a low-voltage issue contributing to the pump not operating like it should. Check your voltage at the pump, maybe you've got a not-so-good connection on either side of the poles. I'd suggest power the pump independently of everything you're powering it with now.
Just a thought.
The DS4 has a transfer pump internal so it does not "need" any psi let alone 9psi as mentioned. The issue is that when a typical lift pump fails it creates significant restriction in the system forcing the transfer pump to do double duty and reducing the return flow volume (cooling) significantly. This is part of the reason why the PMD's are so prone to fail when mounted on the pump.
John,
My lift pump harness powers the lift pump from a large ring eye and heavy gauge wire totally independent of any factory wiring. You could use this harness on a lawnmower, test bench, or anything with 12v system.
Burning Oil
03-15-2012, 10:11
@BURNINGOIL
my thoughts to your thoughts Mr Spock....
thats a great looking pump ,just the price puts me off. is the fuel pressure that critical that it needs EXACTLY 9 psi? isnt a positive pressure feed still positive?
.
The ds4 IP will work the best with any psi above 8. All else being equal by just changing from a stock LP to a Walbro FRC10 you will hear a difference in the engine and fill the improvement on the road. As far as price, Walbro is a better built pump, rebuildable, has optional clear bowl, capable of hot WVO also, holds up to bioD, have not had a single problem with one yet and is $139. Stock a/c delco is $95ish, but only puts out max of 7psi at idle and not rebuildable.
According to Stanadyne's own TSB the ds4 should recieve 9psi. I realize the IP has a transfer pump, but if 0 or 1psi is being delivered via LP the engine will run poorly under load compaired to 6-10psi.
I do agree lack of fuel to IP can reduce the life of the PMD also. IMO even with a good fuel supply the temp swings are just to much for the PMD (mounted on IP) especialy in cold climates. Going from very low temps to engine operating temps several times a day just kills them.
phantom309
03-15-2012, 15:00
this works for me,.
14psi or so,. fills the filter real quick it,.cheap too,.
http://i39.photobucket.com/albums/e157/wtfuashols123/MVC-075S-1.jpg?t=1323563124
Nick
arveetek
03-20-2012, 13:38
I received the AC Delco pump and installed it last night. Right away it primed up quickly and pressurized faster than the previous Airtex pumps. It also ran higher pressure - up to 9 psi. The Airtex pumps put out 7 psi at best.
Started it up, drove about 15 miles, and all seemed good. I noticed pressure dropped off after driving, and was hovering around 3 psi while idling.
I drove to work this morning (22 miles), and she started sputtering and finally died in the parking lot. I had 0 psi now. I couldn't get the pump to pressurize at all. After sitting for a few minutes, I was able to get it to pump up to 9 psi, but after starting the engine, it fell instantly to 0 psi.
I shut it off, primed the system, went to 9 psi, started it up, and it went right back to 0 again.
After sitting until lunch time, it would prime up to 9 and then held around 4 psi while idling. After driving a few miles, it dropped to around 2 psi.
Obviously there is still some restriction in the suction side. It's bad enough that it causes the engine to stall. Neither the electric lift pump nor the transfer pump in the IP is enough to pull fuel from the tank when the problem arises. It appears that the problem goes away after sitting a while. I'm guessing something in the pickup assembly or soft rubber hose is clogging the flow of fuel after a short period of time.
I guess I'll be dropping the tank again! (for a third time)
I'm really going to have inspect the sock. I noticed on my old OEM pickup assembly, the sock was removable. On the new unit, I couldn't get it to come off the pipe.
Casey
Burning Oil
03-20-2012, 14:44
Sock will come off. Did you ever blow out the lines? While tank is down it would be a good to blow them out. Use a clean catch bucket so you can see what comes out. I did mine one time and was shocked at the amount of crap that came out.
If you remove tank sock You can keep your A/C pump and add a 30 micron prefilter to it. I make the special fittings for it just let me know if interested.
DmaxMaverick
03-20-2012, 16:03
Try the same thing with the fuel cap loose (or removed). You have more than just a flow problem. Still, it's not the sock, or you wouldn't have had the trip you did. It's plugged, or it's not. In all likelihood, the tank is not venting, and the system is suffering under vacuum once it's ran a while.
Try the same thing with the fuel cap loose (or removed). You have more than just a flow problem. Still, it's not the sock, or you wouldn't have had the trip you did. It's plugged, or it's not. In all likelihood, the tank is not venting, and the system is suffering under vacuum once it's ran a while.
I second this.
arveetek
03-21-2012, 05:38
I didn't make it home last night. I made it within 2 miles of the house. I had 0 psi on the fuel pressure gauge, and trying to prime the system resulted in no movement of the needle at all. While I was there I removed the fuel cap, but no change.
I came back 30 minutes later to tow it home. Pushed it in the garage, tried priming it again and instantly had 9 psi. Started right up, and held a constant 5 psi while running for about 10 minutes or so before I called it a night and went to bed.
I've tried leaving the cap loose or off before while troubleshooting, and haven't noticed a change.
Whenever the problem occurs, I get zero fuel flow. Let it sit a while, and she's back to normal.
Casey
FYI radiator shops generally also do gas tank repair. I'd suggest getting fuel level as low as you can and drop the tank then inspect and have it cleaned/flushed to be certain it's not a bio fouling situation. Otherwise you might end up back inside again.
ginger743
03-21-2012, 07:07
Have you checked the voltage at the pump while it's failing ? Seems you've checked everything else. Put a volt meter across the leads going to the pump when it's on and your pressure is zero. You may have a serious voltage drop at the pump.
Jerry
The problem is most likely in one or more of the Rubber hoses.
Cut them all off the system, install a ferrul fitting on the steel line then remove the fitting. Use the ferrul as a retaining "Bump" install all new hose and clamp with stainless clamps.
The issue can be on the suction side or the pressure side.
The Transfer pump in the IP can suck really well and if there is a blockage it will pull a vacuum and suck the filter dry very fast.
What happens is that the hose core delaminates from the reinforcing layer and then can suck flat and choke off the flow.
On the pressure side a "flap" of inner hose liner can flip into the flow and stop up the line, the resultant restriction allows the transfer pump to pull a high vacuum on the line and suck the filter dry.
REPLACE the rubber, all of it, on both the feed and the return lines.
Blow out the steel for good measure too.
This should correct the problem for good.
As mentioned before, Mickey mouse a 5 gallon fuel jug and sit it in the passenger floor area and run a hose to a lift pump and rig it out the window and under the hood as a test.
I personally would just replace the Rubber and be done with it.
Good luck
Missy
Have you checked the voltage at the pump while it's failing ? Seems you've checked everything else. Put a volt meter across the leads going to the pump when it's on and your pressure is zero. You may have a serious voltage drop at the pump.
Jerry
*2
I am wondering if the location you are drawing power from is expanding from high current draw and loosing contact.
arveetek
03-21-2012, 08:14
Thanks for the suggestions everyone.
I have checked voltage at the pump several times, but I have not been able to check it when the symptoms appear. I'm usually on the side of the road when it quits for good! ;)
All rubber lines from the lift pump forward are brand new. I installed a new Racor filter, and ran my own rubber line from the lift pump up to the filter, and ran a new line from the filter to the IP. The only stock rubber line left is between the hard steel line on the frame rail and the fuel tank.
I haven't had any biodiesel in the tank in over 4 months. I'm still going to drop the tank and see what's in there once again.
Casey
ginger743
03-21-2012, 08:26
Hi Casey,
It wouldn't be too difficult to run an alternate power source to the pump , heck you could even use a cigarette lighter plug for the power source. The only " problem " would be to open the leads to the pump which you would have to splice back together after you finish the test.
Wouldn't take very long to do the tests.
You could also add extension leads to your voltmeter so you could monitor the voltage as you drive and catch it when it fails.
Jerry
Replace that last piece of rubber line while your at it.
The issue is obviously a failure to deliver fuel.
If you have replaced all the stuff from the Lift pump forward then the issue is either the rubber line that connects the tank or the pickup tube somehow.
I have seen many rigs that have a failed lift pump run just fine until a filter change, then it gets noticed as the filter will not refill.
This has definately gotten to be interesting for sure.
Missy
arveetek
03-21-2012, 12:15
If you have replaced all the stuff from the Lift pump forward then the issue is either the rubber line that connects the tank or the pickup tube somehow.
This has definately gotten to be interesting for sure.
Missy
I don't think 'interesting' is the right word here! :D
Yep, everything from lift pump forward is new, including the injection pump!!! I'm pretty sure I ruined the original IP with this whole fuel starvation fiasco. I'm sure it was old and weak anyway, but still....
Casey
arveetek
03-23-2012, 06:16
It was the stupid 'sock' in the tank.
It passed the visual inspection twice before. Last night I dropped the tank again, and this time I took the sock off and tried to suck some air through...and it wouldn't hardly pass any air through!!
The 'sock' was new less than 20K miles ago. But, it's a different design than the OEM sock. I took the old OEM sock off my old pickup assy, and it had no restriction whatsoever. The OEM sock also has a bypass valve built in, that will allow fuel to come in through the end if the sock gets restricted.
The old sock is nearly round with nothing inside. The new sock is flat with a plastic mesh inside, so it's actually several layers. Even after cleaning it, it still didn't flow much air.
(New sock on left, OEM sock on right)
http://www.thedieselpageforums.com/photopost/data/500/medium/Tahoe_001.jpg
I put the old OEM sock back on the newer pickup assembly. I also blew the lines out from the lift pump back. Got a little bit of junk out, not much. I also replaced the rubber line from the tank to the hard line.
With the last Airtex pump and before these changes, the best pressure I had before starting was 7 psi, dropping to 4psi while idling, with the pressure falling to zero after running a short while.
http://www.thedieselpageforums.com/photopost/data/500/medium/March_2012_003.jpg
With the new AC Delco pump and the repairs made last night, I have 10.5 psi before starting, dropping to 6 psi while idling, with no further pressure drop after running.
http://www.thedieselpageforums.com/photopost/data/500/medium/Tahoe_002.jpg
I actually made it to work with no problem! I still had 6 psi while idling after driving 22 miles.
After all this time, it was that stupid sock.......
I do think that the aftermarket socks are probably not the best product to be putting in our diesel fuel tanks. It could be that our homebrew bio fuel may have clogged this sock as well.
Thanks for all the advice everyone. Sorry I didn't follow all of it as soon as I should have.
Casey
Burning Oil
03-23-2012, 22:24
Said it atleast 6 times to relocate the sock to the trash can.
Then you went and stuck the sock back in there!!?
Keep an eye on it as you will probaly be droping the tank again.
Could have saved the cost of the IP as Im sure it was fine.
arveetek
03-25-2012, 14:38
Still running great! Been driving all weekend without a single drop in fuel pressure.
I even had time to change the tranny fluid yesterday, which was long overdue. I did the flush out method: took the tranny cooler return line loose and pumped the old fluid out into a clear container. Worked really well. That old fluid was looking nasty...fortunately it didn't smell burnt.
I'm so glad to have my favorite vehicle running right once again.
Casey
Burning Oil
03-25-2012, 15:58
Thats great, hope it runs well for along time.
How much fluid did you go through? I did that once and used like 16 qts before it ran clear.
arveetek
03-25-2012, 19:40
Thats great, hope it runs well for along time.
How much fluid did you go through? I did that once and used like 16 qts before it ran clear.
I show that the 4L80E holds 14 quarts on a full fluid change. Yes, I ended up using a full 4 gallons when it was all said and done.
That tranny holds a lot of fluid!
Casey
SickSpeedMonte
06-27-2012, 07:09
Wow, I have had almost the exact same experience as you...
When I got my '93, the underside was rusty. I had to replace the brake lines, trans cooler lines, and the fuel lines. While replacing the fuel lines, I noticed that the lines on top of the tank were shot, so I replaced the sender with an aftermarket one from Quanta Products.
I replaced the fuel filter as well. At first, all was well. I even towed my C230 about 75 miles to get it fixed at a dealer. A few weeks later, it started starving for fuel. The bowl would not fill just like yours. I think the air gets in there when you crack open the bleeder by the way; there is a vacuum in there otherwise, which is why the IP doesn't like it and the truck doesn't run.
So I replaced the LP, seemed easy enough to do and the Airtex wasn't too expensive from Advance Auto. Still had the problem.
I couldn't hear the LP running with the truck running (too much other noise) and I couldn't get fuel to the bowl unless I jumped the LP, so I figured the OPS took a dump. I got a Delco OPS and did the relay mod while I was in there. Bled the system, and still had the problem when the truck warmed up. It happened when I was low on fuel, so I put 5gal in it and the truck ran home fine. So at this point, I'm thinking that either the tank is creating a vacuum, or the pickup isn't picking up. The next time it happened, I cracked the cap and it didn't help... so out comes the tank again.
The sock was brand new (<100 miles, clean as a whistle), so I verified that the pickup depth was right, and it was. I pulled a vacuum on the pickup, and it held. I verified that there were not clogs in the lines and no kinks in the soft portions, put it back together, and still had the problem a few days later. It was only happening when the truck warmed up, consistently. So I swapped the Airtex LP out under warranty, and I still have the problem.
So then I started talking to a parts supplier tech guy (don't want to name names...) and he told me to get a gauge on the supply line. I get one and install it just before the filter to see if the LP is pumping right. I also pulled the filter out thinking maybe there is a clog in there somewhere. I blew air in the supply line of the fuel manager, which blew the little spring for the heater out. Put it back together and nothing changed. The gauge showed 4psi at idle and less than 1 when I revved it, and then it cut off.
Then he instructed me to replace the fuel manager because there is no way I blew air in there without blowing up seals. So I figure if I have to replace it, I'd might as well take it apart and see what happened, maybe fix it with new seals. The thing was perfectly fine, no blown seals. But now I have managed to render my heater unuseable while trying to disassemble it. The insulation on the wires was all gummy and now there are exposed wires. The fuel heater is so much money that it's only like $10 more to get the whole fuel manager, so it looks like I'll be spending ~$200 on that...
I was also told that if the regulator/check valve on the return line of the IP is suspect, to just replace it. I took that off and blew some air at it (never actually touched the nozzle to the check valve to try to create a seal or anything). Still somehow, I think I might have trashed that. There is a black O-ring in there that looks like it rolled out of its seat.
Now that I have read your thread, I'm pretty sure that I have been chasing my tail this whole time and it was that damn sock. I don't have the stocker anymore, but I did a little experiment last night. I disconnected the fuel line going into the LP and blew shop air towards the tank, trying to blow the sock off. I don't know if it worked or not. I put it all back together, got plenty of fuel to the fuel bowl, but it wont start. I think that little check valve is indeed comprimised.
So from here, I need to replace that check valve, get a fuel heater one way or another, and see if it still stalls under load. Regardless of what happens, I think I still need to drop the tank and get an OE sock on there. I don't know if I should stick it out with the Airtex LP or try to return it towards a Delco...
Wow, I have had almost the exact same experience as you...
When I got my '93, the underside was rusty. I had to replace the brake lines, trans cooler lines, and the fuel lines. While replacing the fuel lines, I noticed that the lines on top of the tank were shot, so I replaced the sender with an aftermarket one from Quanta Products.
I replaced the fuel filter as well. At first, all was well. I even towed my C230 about 75 miles to get it fixed at a dealer. A few weeks later, it started starving for fuel. The bowl would not fill just like yours. I think the air gets in there when you crack open the bleeder by the way; there is a vacuum in there otherwise, which is why the IP doesn't like it and the truck doesn't run.
So I replaced the LP, seemed easy enough to do and the Airtex wasn't too expensive from Advance Auto. Still had the problem.
I couldn't hear the LP running with the truck running (too much other noise) and I couldn't get fuel to the bowl unless I jumped the LP, so I figured the OPS took a dump. I got a Delco OPS and did the relay mod while I was in there. Bled the system, and still had the problem when the truck warmed up. It happened when I was low on fuel, so I put 5gal in it and the truck ran home fine. So at this point, I'm thinking that either the tank is creating a vacuum, or the pickup isn't picking up. The next time it happened, I cracked the cap and it didn't help... so out comes the tank again.
The sock was brand new (<100 miles, clean as a whistle), so I verified that the pickup depth was right, and it was. I pulled a vacuum on the pickup, and it held. I verified that there were not clogs in the lines and no kinks in the soft portions, put it back together, and still had the problem a few days later. It was only happening when the truck warmed up, consistently. So I swapped the Airtex LP out under warranty, and I still have the problem.
So then I started talking to a parts supplier tech guy (don't want to name names...) and he told me to get a gauge on the supply line. I get one and install it just before the filter to see if the LP is pumping right. I also pulled the filter out thinking maybe there is a clog in there somewhere. I blew air in the supply line of the fuel manager, which blew the little spring for the heater out. Put it back together and nothing changed. The gauge showed 4psi at idle and less than 1 when I revved it, and then it cut off.
Then he instructed me to replace the fuel manager because there is no way I blew air in there without blowing up seals. So I figure if I have to replace it, I'd might as well take it apart and see what happened, maybe fix it with new seals. The thing was perfectly fine, no blown seals. But now I have managed to render my heater unuseable while trying to disassemble it. The insulation on the wires was all gummy and now there are exposed wires. The fuel heater is so much money that it's only like $10 more to get the whole fuel manager, so it looks like I'll be spending ~$200 on that...
I was also told that if the regulator/check valve on the return line of the IP is suspect, to just replace it. I took that off and blew some air at it (never actually touched the nozzle to the check valve to try to create a seal or anything). Still somehow, I think I might have trashed that. There is a black O-ring in there that looks like it rolled out of its seat.
Now that I have read your thread, I'm pretty sure that I have been chasing my tail this whole time and it was that damn sock. I don't have the stocker anymore, but I did a little experiment last night. I disconnected the fuel line going into the LP and blew shop air towards the tank, trying to blow the sock off. I don't know if it worked or not. I put it all back together, got plenty of fuel to the fuel bowl, but it wont start. I think that little check valve is indeed comprimised.
So from here, I need to replace that check valve, get a fuel heater one way or another, and see if it still stalls under load. Regardless of what happens, I think I still need to drop the tank and get an OE sock on there. I don't know if I should stick it out with the Airtex LP or try to return it towards a Delco...
Take the sock completely out and put an inline fuel filter/screen in pre LP-much easier to change when it gets dirty when on the frame rail.
DmaxMaverick
06-27-2012, 13:58
Take the sock completely out and put an inline fuel filter/screen in pre LP-much easier to change when it gets dirty when on the frame rail.
To repeat what I've said before.....
In my educated opinion, this is not good advice. Add a lift pump pre-filter if you wish, but do not remove the sock as a course of corrective or preventive action. If your sock is plugging, or giving you ANY grief, you have a SERIOUS fuel quality problem. The sock is nothing more than a relatively coarse screen, which will catch metal flakes, pebbles, sand, algae or other large debris that may plug the pickup tube inlet. If your sock is plugging up, you would have had to replace dozens of filters by this time. If the sock is plugged, the tank and entire fuel system needs to be cleaned and flushed. It's that simple. I hear the sock getting blamed as a "problem", while it almost never can be. Of course it can fail, but it will never cause the problems it is blamed for. It will almost always be the result of a problem, and almost never be the cause of one.
To repeat what I've said before.....
In my educated opinion, this is not good advice. Add a lift pump pre-filter if you wish, but do not remove the sock as a course of corrective or preventive action. If your sock is plugging, or giving you ANY grief, you have a SERIOUS fuel quality problem. The sock is nothing more than a relatively coarse screen, which will catch metal flakes, pebbles, sand, algae or other large debris that may plug the pickup tube inlet. If your sock is plugging up, you would have had to replace dozens of filters by this time. If the sock is plugged, the tank and entire fuel system needs to be cleaned and flushed. It's that simple. I hear the sock getting blamed as a "problem", while it almost never can be. Of course it can fail, but it will never cause the problems it is blamed for. It will almost always be the result of a problem, and almost never be the cause of one.
While your advice is correct when dealing with the stock diesel sock,it does not remedy the condition many people face when buying aftermarket sending units that even though are speced for diesel use-have been shipped with gasoline socks.
The socks for gas use are a much finer mesh and often inhibit the flow of diesel that is a much thicker fluid-especially when the fuel is exposed to colder temps.
DmaxMaverick
06-27-2012, 14:24
While your advice is correct when dealing with the stock diesel sock,it does remedy the condition many people face when buying aftermarket sending units that even though are speced for diesel use-have been shipped with gasoline socks.
The socks for gas use are a much finer mesh and often inhibit the flow of diesel that is a much thicker fluid-especially when the fuel is exposed to colder temps.
It doesn't matter which sock. The aftermarket socks may be finer, but still so coarse that it will not cause issues with an otherwise healthy system and quality fuel. The area of the sock that will pass fuel (the holes) is many times greater than the area of the inlet. Most heavy equipment fuel tank socks are many times more fine than any automotive sock, and they are usually metal. The same rules apply, regardless of the sock. If it's plugging, you have fuel quality issues. If it's temperature related, the sock is the least of your worries. By the time fuel won't pass the sock, your pump can't pump, and the fuel manager filter will not pass it, heater or not, sock or not. If the fuel gets too "thick" when it's cold, you need to treat the fuel, or warm it up. It's really only that simple. Sock removal for any on-road vehicle is not a solution to any problem. Replace it, perhaps, after the cause of the problem has been fixed, if it makes you feel better.
No problem with your reasoning but if you haven't noticed the many many threads about problems with gas socks on diesel sending units restricting fuel over the last year or more then thats ok too.
SickSpeed check Amazon.com for the fuel filter unit -( ACDelco 10226035 ) just got one from them for $95. They also sell the Delco sending units ( ACDelco FLS1089 )cheaper than most. No taxes and free shipping most of the day. Also just ordered my Delphi injectors from them - $100 cheaper than anybody already.
Good luck figuring it out
Brad
Burning Oil
06-27-2012, 15:19
Also, a truck can get a bad batch of fuel and pass that tank of fuel, but leave crap on the sock. That seems to be what I see most. So, there is really nothing to cure as far as the problem/source (except maybe don't fill up with the same fuel again). Point is the fuel quality is the problem we all know that. If you get one tank of algae fuel this does not mean you will always have algae until you drop the tank and clean it, you might be just fine if you can burn that tank out, but now the sock/filters probaly need replaced.
I would rather change a $10-15 pre lp filter than to drop the tank and do the whole sock thing.
I agree with Dmaxmav that the sock is not the problem, its the fuel quality. I just recomend a easier way to get the fuel system flowing again if you do get a real bad problem.
DmaxMaverick
06-27-2012, 15:57
No problem with your reasoning but if you haven't noticed the many many threads about problems with gas socks on diesel sending units restricting fuel over the last year or more then thats ok too.
That's the problem. It's an easy scape-goat, when it isn't the problem. It's like someone blaming the spoon for being fat.
greatwhite
06-27-2012, 18:35
I also believe the tank strainer is a red herring 95-99% of the time it is blamed.
My 98 has a raptor 100 pumping 12 psi and pulling through the strainer and a 14" 30 micron prefilter.
Original tank strainer and 429,000 kms on it. Taken fuel from stations across literally the entire continent. Everything from truck stops to the smallest places in the middle of nowhere. Even had to syphon from an old farm trucks tanks that had been sitting for a couple years once when we found ourselves lost in the middle of nowhere and running too low on fuel (yes, the owner knew I was doing it!).
Nary a bobble or complaint because of the tank strainer.
But like any part, it can fail, clog or do something totally off the wall. Hence the 95-99% time rating.
The OEM deign has a bypass built in so even if it fails to pass fuel it will still flow.
Now if someone gets in there and installs non OEM or the wrong parts, all bets are off.....
arveetek
06-27-2012, 20:02
To repeat what I've said before.....
In my educated opinion, this is not good advice. Add a lift pump pre-filter if you wish, but do not remove the sock as a course of corrective or preventive action. If your sock is plugging, or giving you ANY grief, you have a SERIOUS fuel quality problem. The sock is nothing more than a relatively coarse screen, which will catch metal flakes, pebbles, sand, algae or other large debris that may plug the pickup tube inlet. If your sock is plugging up, you would have had to replace dozens of filters by this time. If the sock is plugged, the tank and entire fuel system needs to be cleaned and flushed. It's that simple. I hear the sock getting blamed as a "problem", while it almost never can be. Of course it can fail, but it will never cause the problems it is blamed for. It will almost always be the result of a problem, and almost never be the cause of one.
I agree with DMAX, don't leave the sock off. However, as I have found out first hand, the aftermarket socks are NOT the same quality as the OEM versions. If I were in your boat, I would spend the money for a genuine GM sending unit with new sock.
The plastic sock that came on my aftermarket unit was shot to crap after 15K miles. I reinstalled my old 200K mile OEM sock, and all has been well since! :D I am currently at 254K miles. I chased my problems round and round, and it was the stupid, cheap, plastic sock that was restricting flow.
I don't think the plastic crap used on the aftermarket sending units is compatible with diesel fuel, especially biodiesel and bio blends. All the little holes in the sock swelled shut and wouldn't let fuel flow through. The OEM sock is not made of plastic, but some other durable material.
I know it wasn't a fuel quality problem, because I chased this problem for months over multiple tanks of fuel. After swapping socks, the problem went away, even though I am still using the same sources of fuel. Also, I tried cleaning the "new" sock with brake cleaner and other solvents, and I could not get it to flow properly. It was definitely a poor quality product.
Again, here is a photo showing the two socks and the different constructions of each.... aftermarket on left, OEM on right:
http://www.thedieselpageforums.com/photopost/data/500/medium/Tahoe_001.jpg
Notice the relief valve on the OEM version.... not even present on the aftermarket unit. The aftermarket version also has a plastic screen inside the outer screen, so it is three layers thick. Very difficult for diesel to flow through.
Casey
Burning Oil
06-27-2012, 21:01
I would'int say its a scape goat when alot of time it actualy is the problem. I know you say dirty fuel...ect is the problem and it is, but now you have a snoty tank sock so it is a problem to. Who wants to drop the tank...blah blah...VS change a spin on filter? not me!
DmaxMaverick
06-27-2012, 21:40
I would'int say its a scape goat when alot of time it actualy is the problem. I know you say dirty fuel...ect is the problem and it is, but now you have a snoty tank sock so it is a problem to. Who wants to drop the tank...blah blah...VS change a spin on filter? not me!
Do it right, or not. Your choice. The socks don't get snotty all by themselves. As I said, they are not the problem, but an indicator of a problem. Be it "dirty" fuel (never said that), contamination, biological, bioDiesel (not an accepted fuel in excessive %, by any OEM or aftermarket supplier), gelled, etc. The correct action is to remove the tank, clean it, and flush the system. Anything less is a band-aid, and/or a leap of faith. Please describe ONE instance when the sock failed, all by itself.
Burning Oil
06-28-2012, 07:33
Its not a Band aid its a modification that addresses a weak point of a system. Are you against modifications? I said I agree with you that the sock is not the problem, but by your analogy then nothing on the truck should be a problem EVER as long as you don't use it, but In the real world its a very good and sound modification. Go ahead and pull your tank if you like. I'll give the spin on filter a chance first. I've had many trucks that needed just the sock removed or cleaned/R&R. The tank was clean. I believe the OP was an example of this? (not going to reread the thread again)
I said "dirty fuel" as a general term, relax.
greatwhite
06-28-2012, 09:32
I wouldn't call the tank strainer a "weak point".
It does exactly what it was designed to do if it's OEM parts.
I do advocate installing a supplemental filter prior to the lift pump though.
In theory, the tank screen can be removed at this point if desired as a 30 micron prefilter will do the screens job for it.
My personal preference is to leave the screen to work in tandem with the prefilter. Screen takes the "gravelly bits" out, prefilter scours down to 30 microns and protects the lift pump, then the main filter scrubs down to 5-10 microns to protect the ip.
That's how mine is right now, workin' fine....
Burning Oil
06-28-2012, 09:38
I wouldn't call the tank strainer a "weak point".
OK, choke point?
greatwhite
06-28-2012, 12:24
OK, choke point?
Nope.
Mine's been doing its job just fine for 14 years and 429,000 kms.
And 2 years ago I threw 1/2 Pushlok and a raptor 100 lift pump at it running 12-14 psi. Still not a wimper.
Hard to argue it's anything less than at least adaquate at its assigned task...
As I mentioned before, nothing is perfect. The tank screen is subject to failure just like any other part.
If people don't like it in there, an external filter will do just as good a job.
You still have to remove the tank to clean it if you get a load of crap in there though.
My prefered method (in a perfect world and limitless budget) would be a tank with a sump feed and a prefilter. Tank gets "messed up" disconnect the feed and let it drain out. Flush it in situ and then hook the lines back up after flushing them from the prefilter back. Change filter and off you go.
I may go that way In the future as I plan to eventually gt an extended range tank built and I'm free to build what I want then. Sure would love to be able to drop 200-300 dollars of diesel in when I run across a scent price rather than getting stuck with whatever is local at the time. Would also be great when hauling the TT....
Can you get those metrome tank senders in custom lengths?
:)
Burning Oil
06-29-2012, 14:05
I give up tring to explane the benefit of removing the tank sock. I'll just say IF one day you (in general) get a pluged up sock you will wish you had the spin on. Funny thing is though, you will want to wait until there is a problem to remove the sock or FSU before doing the mod.
I can build to order some custom length Metrum Rod FSU's.
http://www.pmdcable.com/index.php?main_page=product_info&cPath=6&products_id=19
stezloco
06-30-2012, 08:39
I'm totally with you on the sock removal thing mate. did mine , now the agglomerator catches anything big enough to get down the fuel pipe and i can see it in the bowl when i service the truck. the coarse mesh filter then traps any floaters trying to get into the electric fuel pump. any fines that get past that will go through the pump and end up in my fuel filter, simple as that.....i am still now getting emails with links to this problem thread......thought it had died ages ago......can it?......please?:(
Without the sock a single particle of sufficient size can completely block fuel flow. The sock prevents that from happening as the entire surface of the sock must be blocked to completely block flow.
arveetek
06-30-2012, 12:20
Without the sock a single particle of sufficient size can completely block fuel flow. The sock prevents that from happening as the entire surface of the sock must be blocked to completely block flow.
Exactly. That's why, even though I experienced sock issues, I still recommend and believe that having a sock in the tank is very important. The sock is not a filter, it is a screen, the first line of defense in clean fuel.
For example, let's say a foreign object gets into the tank, and that object happens to be just small enough that it get sucked up into the pickup tube. It then gets lodged in the first elbow and can't travel any further. Immediate fuel flow has stopped.
Or let's say several smaller objects have gotten into the tank, and they also get sucked up into the fuel system and then become lodged, even before reaching any kind of aux. filter. Fuel flow has stopped.
By having a larger surface area to draw through, the chances of fuel flow becoming completely stopped have diminished greatly. The sock helps spread out the fuel intake into the suction tube. It's like having two drains in a swimming pool. One drain is very dangerous, for if something gets sucked down on that drain by the filter pump, something terrible happens: either the water flow is obstructed, or a person's body is damaged or even held under water by the suction. By adding a second drain opening that is tee'd into the first, if one drain gets blocked, the second takes over and nothing serious happens. Water continues to flow.
Casey
arveetek
06-30-2012, 12:23
As the original poster of this thread, I am exercising my right to close this thread. I don't like the direction things are headed. I have documented my troubles, found a solution, and expressed my opinions. I think enough has been said on this issue.
Thanks for all help and insights on this problem!
Good day,
Casey
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